Automatic circuit breaker



y 1951 F. J. M. THEUNISSEN 2,551,302

AUTOMATIC CIRCUIT BREAKER Filed Dec. 3, 1945 8 ax-ngrwuc I fm/emarFkmvcozs J94 M215 EEC/1mm x Mal 412 #4,.

Patented May 1, 1951 AUTOMATIC CIRCUIT BREAKER Francois Jean MarieTheunissen, Brussels, Belgium Application December 3, 1945, Serial No.632,441

In France April 23, 1940 Section 1, Public Law 690, August 8, 1946Patent expires April 23, 1960 '7 Claims. 1

This invention relates to circuit-breakers having a magnetic relay or aninstantaneously act-- ing release coil through which the current flowingthrough the circuit-breaker passes.

In known circuit-breakers, the attraction of the movable armature ofthis coil efiects the liberation of a mechanical release system (bypawl, knuckle joint, etc.) rapidly driving the movable contact in thedirection causing opening of the circuit. In this type of apparatus thetime of disconnection of a circuit-breaker comprises the time ofmechanical opening, that is to say, the time necessary to manipulatepawls and for the successive placing in motion of the different parts ofthe mechanism, up to the moment when the fixed and movable contactscommence to separate, and the time or" the electric breaking of thecircuit, that is to say, the time necessary for the extinction of theare which strikes between the contacts on the commencement of theirseparation.

The present invention has for its object to reduce the time of themechanical opening of the circuit and this object is achieved byreducing or even eliminating all the successive movements, by causingthe movable armature to act directly on the movable contact. It is wellknown that such arrangement considerably reduces the time taken by themechanical breaking of the circuit, but they present the drawback ofcausing, at certain densities of the current, rapid vibrations of themovable contact which are of such a nature as to weld together the fixedand movable contacts. This is the case when the circuit-breaker istraversed by an alternating current the intensity of which approachesthat necessary to cause the complete attraction of the movable armature.

These drawbacks are avoided in the case of the present invention by thefact that, apart from the direct action of the movable armature on thecontact system, the armature acts also to operate a releasable systemfor producing a displacement of said movable contact. Thus the movablearmature acts following the principles of the invention, not only tofree the releasable system of release comprising generally a springtending to cause the opening of the contacts as soon as the releasesystem is unlocked or "freed, but also it transmits its impulse directlyto the movable contact (or its equivalent holder), independently of thesystem of release, in such manner that the efiort of attraction of thearmature is added to the action of the release spring. It should benoted that whenever referonce is made herein to action on the movablecontact, it must be understood that this includes an action on anassociated part or" this contact or on its holder.

According to the one embodiment of the invention, the movable armaturesystem comprises two distinct armatures one of which is termed theprincipal and is intended to act on the movable contact by a directkinematic connection, whilst the other, termed auxiliary controls thefreeing of the release system. This auxiliary armature moves against afeeble resetting spring, so that it is attracted by an intensity ofcurrent below that corresponding to the attraction of the principalarmature.

According to this embodiment, the principal armature acts from thecommencement of its displacement, to shift the movable contact, thismovable contact being carried by the principal armature itself or by apart actuated directly by this armature.

According to another embodiment, the movable armature causes, during itsinitial movement of attraction, the intervention of the release system,the direct action of the armature on the movable contact taking placeonly after the termination of the movement necessary to cause the saidintervention. After having freed the release system, the movablearmature therefore exerts, independently of this system, a strikingaction directly on the movable contact of which it thus accelerates thedisplacement.

The system of release may with advantage be that serving for the delayedrelease when the circuit-breaker is provided with such a release.

In order to retain the movable contact in its open position after themovable armature has ceased its action, the contact pressure between thefixed and movable contacts may be obtained, following the principles ofthe invention, by a rocking lever intended to be operated by the movablearmature and subjected to the action of a resetting spring the line ofaction of which passes, on its manipulation, to the other side of itspivotal axis. Furthermore, the end of the spring associated with thesaid rocking lever is attached to another rocking lever the pivotalpoint of which is fixed in such manner that, in the position ofengagement of the circuit breaker, the line of action of this springpasses between the pivotal points of the two said rocking levers. Thissecond rocking lever is retained against the action of the spring by apawl constituting with this rocking lever, the release mechanismspecified above.

The annexed drawings show by way of nonrestrictive example severaldifierent methods of carrying out the invention.

In the drawings:

Figures 1 to 3 are diagrammatic views showiizng three differentembodiments of the inven- In these difierent figures, the movablecontact 2 is carried by a rocking lever 3 pivoting about a fixed point3a. This rocking lever is subjected to the action of a spring l, oneextremity of which is pivotally attached to the rocking lever 3 at 3b,whilst the other is pivotally attached to a second rocking lever 5 thatis itself pivotally secured as at 511. The arrangement of the rockinglevers 3 and 5, as also of the spring Q is such that in the position ofengagement, that is to say, that shown in the figures, the line oraction of the spring passes between the pivot points 3a and 5a of thetwo rocking levers. Under these conditions, the spring efiectivelyapplies the movable contact 2 against a fixed contact 6. The rockinglever 5 is retained in the position shown by a pawl 7 adapted to beactuated by the extremity of a bimetallic blade inserted in the circuitof the fixed and movable contacts through the winding of a release coil9. The extremity of the bimetallic blade acts as shown, on asupplementary arm l rigidly connected to the pawl 1; in the case of anover-load, the bimetallic blade 8 causes the displacement of the pawl I.The second rocking lever moves in the direction of the arrow X under theaction of the spring 4 until the line of action of this spring haspassed on the other side of the pivotal point 3a. In practice a stop 5bwill be provided for the lever 5. From this moment, the spring 4% actsto displace rapidly the contact-carrying rocking lever 3 and to effectthe opening of the circuit. For proper operation, a suitable stop forlever 5 is provided, such as is shown at 5b.

In the case of Figure l, the movable armature of the release coil 9 isconstituted by a core ll sliding about a thrust rod 12 of non-magneticmaterial and bearing directly on the rocking lever 3. If a considerableoverload should occur the core I l moves against the action of itsfeeble resetting spring 13 until a rod is integral with the core abutsagainst the lever arm H3, and displaces the pawl I thus causing therelease. On the occurrence of a short-circuit, the core ll acts not onlyin the manner described above, but it also carries along with it thethrust rod I2, by contacting with a collar Ma. The thrust rod I2 acts tocause the immediate displacement of the contact-carrying rocking lever 3and thus causes the opening of the circuit in a very short space oftime, independently of the movement accomplished by the release system5'i.

In Figure 1, upward movement of the armature reacts through spring 13 onrod !2 and tends to displace it. At first, however, stem I2 is held bylever 3 urged by spring 5, which is sufiicient to enable the armature totravel the short distance required for actuating lever l8 and releasingcontact 2.

In the case of Figure 2, the core ii is keyed directly on the thrust rodI2. An auxiliary armature i5 is slidably disposed on this thrust rod,in. association with a feeble spring 16. In the case of a considerableover-load, the core I I does not have an actuating force suflicient tocause the direct displacement of the rocking lever 3. However, theauxiliary armature i5 moves and compresses the spring It and operatesthe pawl 1 through the intermediary of a lever i1 and an arm [8. On theoccurence of a short-circuit, the core II causes oscillation of therocking lever 3 independently of the movement which might have beencommunicated to this rocking lever by the liberation of the releasesystem 5, i by the auxiliary armature 15.

In the case of Figure 3, the operation is similar to that of Figure 2except that the action of the auxiliary armature ii: on the pawl l takesplace through a rod system 1% bearing against a conical part of thisauxiliary armature to.

Naturally, a similar arrangement may be applied to the case of Figure l.

The invention is also not restricted to the method of release shownsince without departing from the scope of the present invention anyother release system may be utilised. Thus in Figures 2 and 3, a systemof magnetic release may be substituted which would be constituted onlyby the principal and auxiliary armatures H and i5 and which acts asfollows; on a considerable over-load, the auxiliary armature i5 isattracted against the action of the feeble resetting spring it? andapproaches the principal armature ii. The dimensioning of the system issuch that at the end of the attraction movement of the armature 55, thereduction of the gap is such that, for the same current, the principalarmature H is strongly attracted and suddenly shifts the rocking lever 3carrying the movable contact.

The invention presents not only the advantage of causing an extremelyrapid separation of the contacts, but also of proportioning the openingeffort to the intensity of the current causing it, since the armature isattracted all the more forcefully the stronger the current. Furthermore, the release spring which, alone, can cause the opening of thecircuit as soon as the movable contact is dis-engaged, may be madecomparatively weak. This has as a result the reduction of the stresseson the pawls, thus increasing the precision of their operation andreducing their wear. This circuit-breaker is particularly useful as asmall circuit-breaker with great circuitbreaking capacity, mounted on abase or in the form of a plug with pins or for screwing.

What I claim is:

1. An automatic circuit breaker comprising a fixed contact, a movablecontact, means normally resiliently urging said movable contact againstsaid fixed contact, spring actuated means movable from one position toanother position tending to open the movable contact, locking means forrestraining the last mentioned means to one position, a release coilthrough which a circuit current .ilows, a liberating member operativelyconnected to said locking means and connected to be responsive to anoverload current through the coil for unlocking said spring actuatedmember, a member directly mechanically connected to the movable contact,and a movable armature for cooperating with said release coil under theaction of said overload current to act first on said liberating memberand subsequently directly on the member directly connected to themovable contact.

2. An automatic circuit-breaker according to claim 1, wherein theliberating member comprises a delayed action element through which thecircuit current flows and means by which it unlocks said releasabledevice independently of said movable armature, under the action of anoverload current which is not sufficient to cause the attraction of thesaid armature by said coil.

3. An automatic circuit-breaker according to claim 1, wherein theliberating member comprises a bimetallic blade traversed by the circuitcurrent and means enabling it to unlock said releasable deviceindependently of said movable armature, under the action of an overloadcurrent which is not sufficient to cause attraction of said armature bysaid coil.

4. An automatic circuit breaker according to claim 1, in which the meansfor urging the movable contact against the fixed contact comprise arocking lever connected to the movable contact and acted upon by saidarmature, a pivotal axis for said lever, and a resetting spring for saidlever disposed on one side of said axis and arranged in such a mannerthat, at the moment of opening of the contacts, the line of action ofsaid resetting spring passes to the other side of said axis.

5. An automatic circuit breaker according to claim 1, in which the meansfor urging the movable contact against the fixed contact comprise afirst rocking lever connected to the movable contact and acted upon bysaid armature, a pivotal axis for said lever, a second rocking lever, apivotal axis for said second rocking lever, a resetting spring for saidfirst lever disposed to have its line of action on one side of saidfirst axis and having its ends attached to said first and second rockinglevers, and the restraining means includes an element retaining saidsecond lever against the action of said resetting spring, the pivotalaxis of said second lever being arranged and located in such a mannerthat, on release of said second lever from said element, the line ofaction of said spring passes to the other side of said first axis.

4 6. An automatic circuit breaker comprising a fixed contact, a movablecontact, means normally resiliently urging said movable contact againstsaid fixed contact, means for displacing said movable contact fromclosed position, a release coil through which a circuit current flows,means for actuating said displacing means in response to an overloadcurrent through the circuit breaker, a rod positioned to act on themovable contact, a main armature mounted on said rod, an auxiliaryarmature carried loosely on said rod and connected for actuating thedisplacing means in response to an overload.

'7. An automatic circuit breaker according to claim 6, wherein saidauxiliary armature is slidably mounted on said rod, and including a weakspring located between the auxiliary armature and an abutment on saidrod.

FRANCOIS JEAN NIARIE THEUNISSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 585,030 Harrington June 22, 189'?1,330,094 Simon Feb. 10, 1920 1,433,952 Kendall Oct. 31, 1922 1,726,233Krantz Aug. 27, 1929 1,989,497 Reed Jan. 29, 1935 2,027,238 LindstromJan. '7, 1936 2,072,163 Frank et a1 Mar. 2, 1937 2,329,362 Swingle Sept.14, 1943 2,345,105 Dorfman et al. Mar. 28, 1944 2,360,684 Jennings Oct.17, 1944 2,370,024 Dyer Feb. 20, 1945 FOREIGN PATENTS Number CountryDate 297,184 Germany Aug. 2, 1930 342,143 Germany Aug. 8, 1919 866,592France May 26, 1941

